Position sensing in intravascular imaging

An intravascular system comprising:

• an intravascular imaging catheter including a drive cable having a proximal end and a distal end, a transducer located in a transducer position near the distal end of the drive cable, a sheath through which the drive cable extends, and an anchor portion;
• a translation mechanism including an interface element configured to engage the drive cable of the intravascular imaging catheter and a translation element configured to engage and translate the interface element, the translation element of the translation mechanism including a groove configured to engage the anchor portion of the catheter to secure the anchor portion and the sheath of the catheter to the translation element such that translation of the interface element relative to the translation element causes the drive cable and transducer to move through the sheath;
• a position sensor including a movable element and a reference element, the movable element having a movable element position that is correlated to the transducer position and the reference element being positioned at or near the groove in the translation element of the translation mechanism, the position sensor being configured to measure the movable element position relative to a position of the reference element;
• and
• an intravascular imaging engine coupled to the intravascular imaging catheter, the intravascular imaging engine being configured to receive image information from the intravascular imaging catheter and position information from the position sensor and to generate a display based on the image information and the position information.

A method for operating an intravascular imaging system that includes

• (i) a catheter having a drive cable including a proximal end and a distal end, a transducer located in a transducer position near the distal end of the drive cable, a sheath through which the drive cable extends, and an anchor portion,
• (ii) a position sensor including a movable element and a reference element, and
• (iii) a motorized translation mechanism including a motor capable of receiving commands for translating the transducer of the catheter within the sheath and a groove for interfacing with the anchor portion of the catheter to hold the sheath in place while the drive cable is moved therethrough, the reference element of the position sensor being located at or near the groove in the motorized translation mechanism, the method comprising:
• receiving a command to move the transducer a predetermined amount;
• while the anchor portion of the catheter is secured to the groove in the translation mechanism, translating the transducer through the sheath by the predetermined amount via the motorized translation mechanism while receiving position information from the position sensor, the position information being used as a feedback signal for automatically controlling the translation distance of the transducer through the sheath and comprising a movable element position relative to the position of the reference element at or near the groove in the translation mechanism, the movable element position being correlated to a position of the catheter's transducer;
• while moving the transducer through the sheath, receiving image information from the catheter at a plurality of transducer positions based on an imaging function performed with the catheter in a patient's blood vessel, the received image information having corresponding position information based on position information received at or near the plurality of transducer positions;
• and
• generating a display based on the image information and the position information.

An intravascular imaging system, comprising:

• an intravascular imaging catheter comprising a drive cable having a distal end and a proximal end, a transducer located at or near the distal end of the drive cable, a sheath through with the drive cable extends, and an anchor portion;
• an interface element configured to engage the drive cable of the intravascular imaging catheter;
• a translation element configured to facilitate translation of the interface element;
• a position sensor including a movable element and a reference element, the movable element having a movable element position that is correlated to the transducer position, the position sensor being configured to measure the movable element position relative to a position of the reference element;
• wherein
• the translation element includes a groove configured to engage the anchor portion of the intravascular imaging catheter such that when the anchor portion of the catheter is engaged with the groove and the interface element engages the drive cable of the intravascular imaging catheter, motion of the interface element relative to the groove of the translation element causes the drive cable to move through the sheath;
• the reference element of the position sensor is positioned on or near the groove of the translation element;
• and
• the movable element of the position sensor is positioned on an element that translates relative to the groove as the interface element moves via the translation element.